Nylon in many shades of green
Recycled, biobased, biotech, made from cleaner processes or difficult-to-treat waste, the new nylon yarns that are in development cover an array of carbon footprint-reducing measures. This broad approach aligns well with a sector that believes polyamide is a premium fibre that delivers premium performance, aesthetics, longevity and sustainability.
Fishing nets, airbags, carpets. These are the materials that polyamide producers need to collect and treat to make recycled post-consumer nylon. It is a much tougher task than spinning beverage bottles back into polyester. For this reason, recycled nylon comes in limited supply, despite technologies that are already in operation. Aquafil’s ‘regeneration’ process comes to mind but all polyamide producers meticulously collect any production waste they have to meet growing demand for recycled content. Even when considering the possibility of recycling used clothing, the sector runs up against a tricky situation: nylon is often blended with elastane, which needs to be separated out.
But with sustainability high on the agenda of brands large and small, demand for recycled nylon is intense. Polyamide producers and spinners are taking measures to address this issue by reducing the carbon footprint of their production processes, which allows them to deliver the industrial quantities their customers request.
The latest developments focus on shifting away from fossil fuels, both to make nylon’s building blocks and to power factories. Israel-based Nilit’s new Sensil By Nature, a polyamide 6.6 yarn, replaces fossil feedstock with a biomass resource, or biogas, and can claim to be 100% biomass balance. The raw material is supplied by German chemicals company BASF that has developed a chemical manufacturing process powered by biomethane, generated by organic waste facilities or landfills. It applies a system known as Biomass Balance, or BMB, to this production line. “In a biomass balance system, inputs and outputs are monitored by a third party,” says Sagee Aran, Nilit’s head of innovation and sustainability. “Depending on the magnitude of non-fossil input, you can allocate a portion of the production as being biomass balance,” he says. This shift to cleaner energy, be it solar, wind or biogas, is an efficient way to be reduce impacts. “We need more sustainable solutions right now, not in some distant future,” he says, adding that BMB “encourages the shift away from fossil resources”. BASF supplies Nilit with a raw material having a 100% biomass balance stamp. “This certifies that our fibre emits less greenhouse gas, but there is otherwise no difference in performance or in consumer experience. Sensil By Nature has the same functionality as conventional nylon,” he says.
Italian polyamide producer Fulgar has also chosen BASF as the supplier of a raw material for its newest yarn, Q-Cycle, which is ‘recycled’ from used tyres. “Q-Cycle is the result of an innovative chemical recycling technology developed by BASF in its ChemCycling project, combined with Fulgar’s spinning technology,” says Alan Garosi, Fulgar’s head of strategic marketing. The raw material that BASF supplies to Fulgar is derived from the pyrolysis of difficult-to-recycle plastics, specifically tyres. “We have chosen this solution as tyres represent a huge quantity of pollutant elements that is difficult to dispose of. They are often abandoned in deserted areas across the planet and when they are incinerated, they emit significant amounts of CO2,” he says. The advantage, again, is that Q-Cycle nylon 6.6 has the same functional and aesthetic benefits as conventional nylon.
Based in Zaragoza, Spain, polyamide producer Nurel is also launching a new yarn made from pyrolised post-consumer waste. This new fibre, a nylon 6, will supplement its recycled yarn offering. “Our production capacity for Reco Nylon, which is mechanically recycled from 100% post-industrial waste, is fully booked,” says Nurel marketing manager, Leyre Quibus. Nurel has launched a vast company-wide programme to measure its carbon footprint across every product category, and from fibre to final garment, she says. “When we have finalised our research, we should be able to compare the impacts of nylon with those of polyester or cotton,” she says, adding that it has chosen to apply the European Product Environmental Footprint (PEF) protocol. Nurel’s parent company, Samca, operates in renewable energies and has installed what it says is the ‘largest’ solar panel facility for ‘self-consumption’ at its synthetic fibre facility.
Looking further ahead, Ms Quibus expects that there will be more textile waste to recycle when the mandatory separate collection of used textiles is implemented across Europe by 2025. This is part of the EU Green Deal and circularity directives. “This will be a major change. It will promote eco-design in textiles and clothing and may contribute to truly circular solutions,” she says.
Cleaner energy
Pending the development of monomaterial designs, and improved collection and sorting of used clothing, this sector is busy rethinking and optimising its production processes. These can have a high impact on a material’s eco-profile, and it is a core issue at Fibrant, a producer of caprolactam, which is the main ingredient for nylon 6. A former division of DSM, now owned by Chinese group HSCC, Fibrant has invested upwards of €40 million in the development of new technologies and in reducing its N2O emissions. “This has enabled us to reduce the carbon footprint of our caprolactam by over 50%,” says Giovanni Henssen, Fibrant’s head of business development and sustainability. “These measures have brought the footprint of our Ecolactam down to 3.3 kg CO2-eq per kg of caprolactam. It is the lowest in the industry, produced at industrial scale,” he tells WSA. He says this rate is roughly 50% lower than the European average, based on data from PlasticEurope, and possibly 70% lower than the global average. Launched in 2021, this new EcoLactam can help achieve the industry’s ambition to reduce its global footprint. “Our customers understand that it is the right way to go. In addition to increased use of recycled or biobased content, it is also important to explain the impact of a material that has a low carbon footprint, which is not an easy a story to pass on to consumers,” he points out.
Fibrant also offers a biobased EcoLactam Bio made from tall oil, a by-product of the wood pulp industry, whose carbon footprint is even lower at around 1.5 kg CO2-eq/kg. Mr Henssen says the company is looking into the possibility of recycling cooking oil as another biobased option. EcoLactam Circular, a third ‘green’ caprolactam, is based on recycled plastic waste.
Optimised processes
Nylon 6, which is made from a single raw material, caprolactam, can be considered ‘easier’ to recycle than nylon 6.6, which is made from two ingredients, hexamethylenediamine (HMD or HMDA) and adipic acid.
An early supplier of recycled nylon 6 made from fishing nets, Korean textile conglomerate Hyosung is planning a major relaunch of the mipan regen-branded nylon it first introduced in 2007. “Recycling technologies for fishing nets have evolved and collecting and sorting processes have been improved upon,” says Mike Simko, the company’s global marketing director for textiles. The company has entered into an agreement with fishermen in Busan, a major port on the south coast of the country, who will be supplying some 300 tonnes monthly of sorted nylon 6 nets. The new 100% recycled nylon yarn will be launched in the first quarter of 2023 and will be available in all of the company’s specialty ranges including versions delivering added moisture management and odour control.
Like its creora-branded spandex, Xanadu stretch yarn and regen polyester, all recycled fibres at Hyosung are certified 100% recycled content. “This is the only way to make a real impact,” says Mr Simko. The company has released LCAs for its recycled creora and polyester, and plans to publish an LCA for the new recycled nylon. “The first two LCAs have shown that our recycled yarns have a carbon footprint that is reduced by two-thirds compared with conventional yarns. The biggest gain in both cases, elastane and polyester, is the shift away from fossil fuels,” he says; he expects the recycled nylon to have a similar profile.
Aquafil, headquartered in Arco, Italy, is gradually expanding its sources of post-consumer nylon waste to make its regenerated Econyl. It now operates two carpet recycling facilities in the US and has acquired a 32% stake in Nofir, a Norwegian company that has developed a high-tech system to collect and trace discarded nets. Earlier this year, Aquafil formed a partnership with Salmón de Chile, the Chilean Salmon Marketing Council, and Atando Cabos, a Chilean cleantech company, to collect and recycle used fishing nets.
From carpets to airbags
For polyamide 6.6 producers, airbags are a key source of possible waste material that can be mechanically recycled into new yarn. Quantities do, however, remain limited. US-based Invista has recently launched a recycled polyamide 6.6, branded Cordura re/cor, which is made mostly from material recycled from its own operations; it is a key supplier of airbag material. “As a major producer of nylon, we are constantly working on yield improvements that have resulted in a continuous reduction of downgraded material.
However, the scale of our manufacturing facilities ensures that we have line of sight to deliver what the industry needs,” said Cindy McNaull (see WSA issue 1, 2022). The new Cordura re/cor is certified 100% Global Recycled Standard (GRS). Invista says it has benchmarked its recycled nylon 6.6 fibre production process with its existing LCA for virgin polyamide 6.6 and found that the recycled version “leads to a decrease in greenhouse gas emissions of 83%. It reduces energy use by 82% and water by 57%. These are clear and quantifiable benefits,” she says.
Spanish nylon specialist Nylstar also offers a mechanically recycled polyamide 6.6 in its Meryl range. It is made from 50% pre- and post-consumer waste blended with 50% virgin nylon 6.6. “We set the bar at 50% recycled content to ensure the same quality and performance as conventional polyamide 6.6,” says Zuzana Vaskova, head of marketing for Nylstar, adding that it is GRS-certified. The company retrieves fibre and fabric waste from its own production and that of its direct customers. It also works with partner brands to recycle their unsold goods or used garments returned to them, as well as with collecting and recycling centres. “As demand for recycled nylon is high, we are investigating all possibilities,” says Ms Vaskova. One of these is to promote the use of 100% Meryl Pure collections, which are made without elastane. “Our Meryl Hydrogen yarn has good natural stretch and is suitable for tops,” she says.
She adds that the company is also exploring the possibility of setting up a recycling centre in the US and working more closely with brands to encourage consumers to return used clothing in exchange for a discount on new purchases. The advantage of developing 100% Meryl Pure products is that the waste generated by Nylstar’s partner mills in Portugal and Spain are pure nylon 6.6. “It is important to promote recyclability by avoiding blends. We believe it is better to focus on the infinite recyclability and circularity of Pure Meryl,” she says.
Biobased and biotech nylons
A biobased nylon derived from castor beans, a polyamide 11, has been on the market since the 1950s, the result of technology developed by Arkema, a French specialty chemicals producer. The high price of this plant-based nylon has limited its use in apparel. Fulgar says its EVO yarn, a bio-based polyamide 10 made from castor oil, has been popular not only with high-end Italian fashion houses but also with fast fashion retailer H&M. This, it hopes, can “break the mould” and allow the product to expand its presence in the mass market.
Rhodia Brasil, a division of Belgian chemicals company Solvay, has recently launched Bio Amni, a new partially biobased nylon. This polyamide 5.6 is made from pentamethylenediamine (PMDA), instead of HMDA, and adipic acid. The PMD, which makes up 47% of its content, is derived from sugar cane, and the adipic acid accounts for 53% and is made from conventional fossil fuels. “The properties of nylon 5.6 are similar to those of nylon 6.6,” says Eduardo Girote, the company’s strategic marketing and business manager for polymers and fibres. It presents a number of processing advantages, including faster and lower-temperature dyeing (30°C), which increases productivity by some 30%, and wearer benefits such as high sweat-absorption and quick-drying properties. Bio Amni is part of Rhodia Brasil’s efforts to reduce its overall impacts and says that sustainable textiles now account for 30% of Solvay’s global polyamide portfolio. Its goal is to reach 50% in the next three years. The company also produces a biodegradable nylon, Amni Soul Eco, which is distributed in Europe by Fulgar.
Genomatica, a biotech company based in San Diego, California, has been working for years on developing biobased and bacteria-powered building blocks for the nylon industry. A biotech caprolactam is being tested by Aquafil. Thanks to in a partnership with German polymer producer Covestro, Genomatica has recently successfully developed a plant-based HMDA. Japanese textile conglomerate Asahi Kasei has announced it will be using it to make plastics for automotive and electronics applications, along with nylon yarns for airbags.
Beyond the basics
A great deal of effort is being put into giving nylon a greener profile. These measures are mostly technical, behind the scenes, process-optimising and cleaner-power steps that, though laudable, do not have high marketing traction. For some of these innovative solutions, such as the biotech raw materials, it is not yet clear how much energy and resources they use and what their actual carbon footprint will be. What is very clear though, in the eyes of its producers, is that polyamide is a premium fibre that delivers premium properties.
Compared to other fibres, and with regard to microfibre shedding, nylon is mostly used as a filament yarn, less often in staple form, and is probably less susceptible to breaking down. It also has high abrasion resistance and tenacity properties, which probably reduce its ability to degrade in normal use. Nylon producers have also developed biodegradable versions of their fibres. Nylstar’s Hydrogen Meryl is especially engineered to shed fewer microfibres. Nilit’s BioCare is designed to decompose in marine environments, and has certified tests to back this claim. Nurel’s Neride Bio has been proven to degrade in soil at the same rate as cellulose, and in landfill. The company is conducting research to assess its persistence in salt water.
For wearers, nylon producers willingly remind the sportswear industry that polyamide does not absorb odours as polyester does. A garment that feels good and looks good for longer will be kept longer, they contend. These properties could make nylon a more durable and more sustainable solution, they insist. But they are pushing for more. The next step that nylon producers are focusing on is promoting mono-component or monomaterial designs and products. They say that they can make a nylon yarn with enough elasticity to avoid the need for elastane. This would help increase the quantities of recycled yarns available, but beyond that, it would be a big step towards circularity and a deeper shade of green.
In its Ecosustainable collection, Italian warp knitter Cifra features recycled nylon yarns such as Econyl by Aquafil, Renycle by Radici Group and Q-Nova by Fulgar.
Credit: Cifra
